Search tips

mRCT search
Phrasing, and keywords containing punctuation
Search operators
Searching, using the "!" operator
"Stem" searching using the "%" operator
Grouping
Quick search

Searching the metaRegister of Controlled Trials (mRCT) - mRCT search
The content of all the trial records in the mRCT has been indexed so that they can be searched efficiently.

In order to search the mRCT:

1. Enter a keyword or phrase into the SEARCH FOR text box.
2. Select one or more registers by clicking one or more of the checkboxes to the left of each register title. To select all registers check the ALL REGISTERS box. By unchecking this box, all the ticks in the other boxes will be removed.
3. You may select the results to be ordered by relevance (i.e. frequency of keyword or phrase), alphabetically, or by register. You may select 10, 20 or 50 records to appear on each results page by selecting from the MAX RESULTS pull-down box.
4. Click the SUBMIT button.

Check out the FIND TRIALS boxes (to the left of the mRCT pages) for the option to search ACTIVE REGISTERS, ARCHIVED REGISTERS, or ALL REGISTERS.

General note: Certain short words such as "the", "in" and "of" are too common to be indexed and are not sought unless they are part of a phrase.

Phrasing, and keywords containing punctuation
In order to search for an exact combination of words, e.g. heart attack, the phrase should be enclosed within quotation marks: "heart attack" OR 'heart attack'.

Quotation marks are also extremely useful when attempting to search using keywords that contain punctuation, for example: hyphens, apostrophes ("beta-blockers", "Alzheimer's"). If the word or words containing the punctuation are placed between quotation marks, records containing them will be retrieved, and the keywords will be highlighted in the retrieved trial record.

Search operators*
Boolean operators (AND, OR, NOT)*
Search terms may be linked using the following logical search filters or operators:

• AND: when used between two words or phrases the AND operator will retrieve all trial records containing both the words or phrases,

e.g. cancer AND radiotherapy

• OR: when used between two terms the OR operator will retrieve all trial records containing either word or phrase (or both),

e.g. aspirin OR paracetamol

• NOT: when entered before a search word or phrase, the NOT operator will not retrieve records containing that word or phrase

e.g. diabetes NOT cancer

[*The AND, OR and NOT search filters are referred to as Boolean operators. Boolean algebra is a system devised by the British mathematician George Boole that combines propositions using logical relationships. All such operators return one of two possible values, "true" and "false". As such, it is well suited to the construction of search queries.]

Searching, using the "!" operator
An exclamation mark (!), or "sounds like" operator may be used to expand queries to include words that are spelled similarly to the specified term, provided that they sound similar to one another. This type of expansion is helpful for finding more accurate results if there are minor variations of spellings in the trial record, particularly US/English spellings.

For example:
ischaemia! would also find records containing ischemia
leukaemia! would also find records containing leukemia
oesophagus! would also find records containing esophagus ; oesophagitis
tumor! would also find records containing tumour

It is helpful to avoid using terms that sound like one another but are contradictory in meaning (e.g. hyper and hypo).

"Stem" searching using the "%" operator
A percentage (%) operator may be used after the root of a word, so expanding the query to include all words "stemming" from that root.

For example:
random% would also find randomize(d), randomise(d), randomisation(s), randomization(s)
schizo% or schizophren% would find schizophrenia and schizophrenic
diab% would find diabetes and diabetic
encephal% would find encephalitis and encephalopathy

Grouping
Brackets (parentheses) may be used to keep together logical groupings and to ensure that the search is processed in a logical sequence, e.g. (cat OR feline) AND health.

Quick search
The final way to search the Current Controlled Trials website is to use the Quick Search box to the left of all pages. By selecting the radio button you may choose to search:

ISRCTN - by entering a word or phrase and clicking the go button, you will search all records in the ISRCTN Register. The results will be displayed in the main section of your screen.

mRCT - by entering a word or phrase and clicking the go button you will search all active registers in the mRCT. The results will be displayed in the main section of your screen.